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Vectors – what are they?. Vectors describe movements i, j and k represent movement in the x,y and z directions. Vectors – How to calculate. To calculate vector BA, subtract: BA = a - b. A. B. O. Vectors - resultants.
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Vectors – what are they? • Vectors describe movements • i, j and k represent movement in the x,y and z directions Maths revision course by Miriam Hanks
Vectors – How to calculate To calculate vector BA, subtract: BA = a - b A B O Maths revision course by Miriam Hanks
Vectors - resultants To find the resultant, add the components of the vectors together resultant Maths revision course by Miriam Hanks
Vectors - magnitude The magnitude of a vector is its length. The notation for this is vertical lines: eg |a| or |PQ| To find the magnitude of a vector, use Pythagoras or the distance formula. Maths revision course by Miriam Hanks
Vectors - Collinearity • To show that 3 points are in a straight line (ie collinear): • Work out 2 vectors and show that one is a multiple of the other • Show that the vectors have a common point Maths revision course by Miriam Hanks
Vectors in real life Sat navs work out their position from satellites in the sky, but then use vectors to decide on a route. Maths revision course by Miriam Hanks
Vectors – Dot product • There are 2 formulae for the dot product on the • formula sheet: • dot product = x1x2 + y1 y2 +z1z2 • where x,y,z are the components of each vector. • dot product = a bcos • where a is the magnitude of vector a (use Pythagoras for this) • Note these 2 formulae equal each other, so: • a bcos = x1x2 + y1 y2 +z1z2 Maths revision course by Miriam Hanks
Dot product of vectors at 90o The dot product of 2 vectors at 90o is zero and vice versa Why? Maths revision course by Miriam Hanks
Dot product of a vector with itself • The dot product of vector a with itself is: • a2 • Why? Maths revision course by Miriam Hanks
The dot product in real life • When is the dot product used in real life? • Computer games programmers use the dot product to find the angle between 2 characters, so they know whether they are facing each other. Maths revision course by Miriam Hanks